1. Field of the Invention
The present invention relates to a test socket for an integrated circuit package.
2. Description of Related Art
Integrated circuits are assembled into packages which have a plurality of external contacts that are coupled to a printed circuit board. The assembled integrated circuit packages are tested within a test socket before being assembled to the circuit board.
FIG. 1 shows a test socket of the prior art. The test socket includes an adaptor 1 that is bolted to a base 2 of the socket. The adaptor 1 contains a plurality of electrical contacts 3 that are connected to the external contacts of an integrated circuit package 4.
The socket has a spring loaded latch assembly 5 which presses the integrated circuit package 4 into the electrical contacts 3 of the adaptor 1. There are typically four latch assemblies located along each side of the socket. Each latch assembly 5 includes a latch arm 6 that is pivotally connected to the socket base 2. The socket base 2 also supports a spring 7 that is connected to a cover 8. Each latch 5 also contains a linkage arm 9 that is pivotally connected to both the cover 8 and the latch arm 6.
The socket has an actuator 10 which pushes the cover 8 toward the base 2 and rotates the latch arm(s) 6 to an open position. The integrated circuit package 4 is then inserted into the socket. The movement of the cover 8 also pushes the spring(s) 7 into a deflected position. When the cover 8 is released, the stored energy of the deflected spring(s) 7 moves the latch arm(s) 6 back to the closed position. The force of the spring(s) 7 is transferred through the link (9) connection to the latch arm(s) 6 to push the integrated circuit package 4 into the electrical contacts 3.
Some packages utilize flat solder pads instead of pins for the external contacts. These types of integrated circuit packages are sometimes referred to as land grid array (LGA) packages. The test socket shown in FIG. 1 was designed to test an integrated circuit which has a 540 LGA package. Integrated circuits have been developed with more than 540 external land contacts.
Test sockets designed for LGA packages require a significantly larger latch force than test sockets designed for pin grid array packages. It has been found that test sockets of the prior art will not adequately couple the electrical contacts to all of the external solder pads of an LGA package. Inadequate coupling between the electrical contacts and the solder pads creates invalid failures during a test routine of the package. This results in the properly functioning integrated circuit package to be discarded.
It would be desirable to provide a test socket that effectively tests LGA packages without significantly changing the test socket of the prior art. Significant changes would require additional tooling that increases the cost of the socket and, ultimately, the cost of producing the integrated circuit package.